The five activists, including one from the SOHR, had been abducted in October last year and killed in December.

The Islamic State group, also known as Isis and locally called Daesh, has reportedly released a video that shows five media activists from Syria being executed. An Associated Press (AP) report says the activists had been killed last year.

"The Syrian Observatory for Human Rights received a copy of a video issued by the 'Islamic state' in Deir Ezzor, where it showed 5 media activists from Deir Ezzor province [sic]," the Syrian Observatory for Human Rights (SOHR) said in a post on its verified Facebook page.

It gave the name of the five as Samer Mohamad al-Aboud, Mahmoud Shaaban al-Haj Kheder, Mohamad Abdulkader al-Essa, Mostafa Haj Hasa and SOHR activist Sami Jodat al-Rabah.

"...[T]hey were executed at the hands of the organisation," the SOHR said in the post, referring to Daesh.

The observer then went on to describe how each of these activists were killed.

"The first one was executed by cutting his throat with a knife, the second activist was executed by tying him to his laptop then tying his laptop to explosives and detonating it inside his house [sic]," said SOHR in the post.

It went on to add that "the third activist was executed by tying him to a metal door and choking him using an iron chain, the fourth one was executed by slaughtering him using a sharp object. [sic]"

It also said: "And the last activist was executed by hanging his camera to his neck and detonating it after tying him it to the balcony of his house [sic]."

The post also said the activists had been executed on charges of "acting against the Islamic state, communicating with outside parties and receiving funds, and other charges [sic]."

The AP report quoted the SOHR as saying that Isis had abducted the five activists in October last year and executed them in December.